No announcement yet.

3D CAD- RAF Browning .303

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
  • Filter
  • Time
  • Show
Clear All
new posts
  • MikeHoulder
    Rank 5 Registered User
    • Dec 2009
    • 245

    Side bars in progress

    This shows the starboard bar without its components. A groove for the swiveling bracket of the front cartridge stop still needs to be added.

    This shows the bar with its components. There is still work to be done on the retaining pawl. The pawl is shown on the same side as the rear cartridge stop for convenience. It should be on the opposite bar.

    The interior view

    This shows the filling piece which goes on same side as the rear cartridge stop

    Clockwise from the top left, this shows the components:
    retaing pawl
    rear cartridge stop
    two ammunition box lugs
    locking pin without wire safeties
    filling piece



    • MikeHoulder
      Rank 5 Registered User
      • Dec 2009
      • 245

      Since my last post, I have been given much better, much larger, much clearer copies of AP 1224 sheets 1 & 2.
      This has meant that I have a better idea of the spacing & size of the cutouts in the side bars. I must send you a copy, Walter.

      In addition, I have been improving my techniques particularly with filleted edges of solid shapes. I feel that with the reflection of light on these edges the parts come to life in a big way. Of, course, thrilled with this effect, I may have over-done it.

      Here is the side bar re-done with the aid of the new AP 1224's. Its dimensions now are very close to the prototype. I can't say exact as I do not have the engineering drawings.

      Here is the new retaining pawl. Its tail is substantially longer and is curved as well.

      Here are two views of nearly all the parts required at this stage. The front cartridge stop is shown but it requires quite a bit of work still as well as the swiveling bracket whose groove is now shown. This bracket is used to lock the front stop in place.



      • oldgit158
        Grand Waster of Time
        • Jun 2012
        • 608

        Fantastic and interesting thread, got me thinking is there any UK company that produce non working replicas of the type that was fitted to Hurricanes and Spitfires complete
        with inert .303 bullets with links.
        "For you Hilts one month solitary watching Downton Abbey"


        • MikeHoulder
          Rank 5 Registered User
          • Dec 2009
          • 245

          I think this Browning Mk II is the one fitted to Spits & Hurricanes.
          It needs the blast tube adapter instead of a cover for the adapter thread.
          Somewhere very recently I've seen a Browning installation in a Spitfire/Hurricane, possibly here, but I can't remember where it was. Perhaps some one can show us where.
          The gun was without the flash eliminator but had, I believe, the muzzle attachment choke.
          Also it seemed to have two chutes one for links and the other an ammunition feed chute.


          • MikeHoulder
            Rank 5 Registered User
            • Dec 2009
            • 245

            Front Cartridge Stop

            Here are my main sources for the front cartridge stop (thanks to Walter)

            Other views of the whole or parts of the gun show the rear of the front stop but the front of the stop is not visible. It has been difficult to determine the configuration of the front of the stop even from these sources. My estimate is that these four photos show three different versions. I've studied them until my eyes popped out. Shall we say that my rendering of the front of the stop uses intelligent guess work.

            Here's the trunnion, the side bars & other bits together with the finished front stop in its location.

            This shows how the front stop is locked in position using the T bracket locked to the pin passing through the side bars and a key way which is in fact part of the trunnion.

            These are two views of the front stop, T bracket and trunnion key way.

            This show how the stop works. The incoming round is held in the centre position by the stop allowing the transport of the round backwards & downwards into the breech of the barrel.

            The reason for this complication is to allow the ammunition belt feed to come from the left or the right of the gun. Release the side bar locking pin. Swivel the T bracket 180 degrees and slide the stop over to the other side. At the same time, change over the retaining pawl and filling piece and re-position the rear stop. With experienced fingers, it could be done in the time it took to type this description or less.

            This shows the parts arranged for a feed from the left of the gun.

            The happiest of new years to all


            • turretboy
              Rank 5 Registered User
              • Sep 2004
              • 561

              Incredible work Mike!


              • MikeHoulder
                Rank 5 Registered User
                • Dec 2009
                • 245

                Help, please

                In my work on the trunnion and ammunition feed area I have ommited the 3/32" skin plate which fills the gap between the trunnion and the side bars. But I can't for the life of me see how the side bars were fixed to either the trunnion itself or to the missing skin plate.

                Can anyone help on this question? All these images come from Walter's collection.

                Here someone has stripped off both the side bar itself and the skin plate. The plate would lie between the two vertical lines. There are only two rivet holes which could possibly relate to the side bars. These are shown with arrows.

                Unfortunately, the following image of the side bar shows that while there is clearance for those two rivets, shown by arrows, there is no internal flange which could join the side bar to either the skin plate or the trunnion. These two images are sections from the same photo.


                Now looking at the top of the trunnion and side bar, the joints between the trunnion, skin plate & side bar are fine, almost as though they were welded and ground flat. The red lines are witnesses to the joints. The inner line is the joint between the trunnion & the skin plate; the outer between the side bar & the skin plate.

                Here is the same image without the witness lines.

                A further thought, if the two rivets indicated in the first image did join the side bar to the skin plate & trunnion, would such a fine joint bwteen them be possible. My argument being that the two rivets lie at the bottom of the side bar and as a result the free join at the top of the side bar could not be as fine as shown in the photo.

                Comments are very welcome. This has peeved me for some time.


                • Walter 63
                  Rank 5 Registered User
                  • Dec 2008
                  • 104

                  Happy New Year to you Mike, and to all other forum members of course !

                  I just have to say it again, your CAD work is absolutely brilliant! Sorry I can't answer your question re how the side bar is fixed to the side of the gun, think we need to call in the help of one of the forum members who have access to a real .303 Browning!

                  Thanks again for the Air Diagram copy by the way.

                  Do keep us updated, it's fascinating to see the virtual gun come together.

                  Best wishes,



                  • MikeHoulder
                    Rank 5 Registered User
                    • Dec 2009
                    • 245

                    And next ....

                    There is some help for the following in Walter's collection and I have found some more in Internet.
                    Bu I need more, much more, info & component shapes.

                    Here's the list of items as it stands today:

                    Transporter plunger
                    Transporter claw
                    Transporter stop
                    Front transporter cam
                    Rear transporter cam

                    Breech Cover
                    Breech cover catch
                    Breech cover catch axis pin with lever
                    Breech cover catch spring
                    Treansporter guide spring
                    Transporter ramp
                    Feed lever
                    Feed lever plunger with spring
                    Feed lever bush and split pin
                    Feed lever stud
                    Feed slide
                    Feed pawl
                    Feed pawl pin with retainer
                    Feed pawl leg
                    Feed pawl leg pin
                    Feed pawl spring

                    Then all the bits for the following assemblies
                    Breech Block
                    Lock Frame
                    Barrel Extension

                    Some of the items can be skipped e.g. pins & springs, but there's a great many parts to draw
                    Any help will be greatly appreciated.


                    • MikeHoulder
                      Rank 5 Registered User
                      • Dec 2009
                      • 245

                      LHS & RHS feed for RAF gun

                      The RAF Browning .303 MkII has its feed base changed from left hand to right hand relatively easily as I've shown above.

                      I've been lucky enough to make contact with Charlie Brown in the States.
                      He has given me a set of engineering drawings sufficient for those internal components I intend to draw.

                      The main difference as far as I can see, to the level I intend to work, is that the US gun is made for a feed only from the left of the gun.
                      So, to draw the RAF gun I have to modify related components from the US drawings using photos of the equivalent RAF ones.

                      So far, I have found four more items which have to be changed to allow a bi-directional feed. These are:
                      Feed lever (belt feed lever US)
                      Feed slide (belt feed slide US)
                      Feed pawl (belt feed pawl US)
                      Breech block (bolt US) (RAF breech block has two channels symmetric about the centre line instead of one to work the feed lever in opposite senses)

                      It is the feed pawl which is causing me problems at the moment. Here it is at a very early stage.

                      The US drawing has the leg of the pawl welded to the barrel of the pawl (as shown)
                      Simply rotating the feed pawl by 180 degrees would cause the pawl hook or leg to engage a thinner part of the cartridge,
                      So this simple solution cannot serve.
                      The photo in RAF AP1641C shows the leg as a separate part to the barrel (pawl) which can be fitted either side of the pawl barrel using a pin.
                      So solving the problem.
                      Unfortunately the AP1641C photo is far too small to show any detail.

                      I wonder if any kind person has a photo of the RAF feed pawl showing the design of the leg or hook that they can give me.
                      The US version has three rows each of eleven teeth on the end of the barrel in order to grip the cartridge more securely.
                      It would be nice to know if the RAF version also had these teeth.

                      It would be nice to know if I could omit them as they are going to be a B*** to draw.


                      • QldSpitty
                        Rank 5 Registered User
                        • Apr 2006
                        • 2621

                        Its like a swiss watch!!!!
                        "If the C.O. ask's you to be Tail End Charlie...just shoot him!!!....A Piece of Cake.


                        • MikeHoulder
                          Rank 5 Registered User
                          • Dec 2009
                          • 245

                          Yes, a swiss watch and cycling more than 19 times a second.

                          Here's a description of the action of the Feed mechanism from AP1641C:

                          I've found two photos (from Walter's collection) showing the underneath of the breech cover.

                          You can see the feed lever diagonally bottom left to top right.
                          The cam grooves are in the breech block itself (see below) into which the knob on the left end of the lever fits.

                          The feed slide moves within the housing to the right.
                          The right hand end of the lever goes through a slot in the housing, connects with the feed slide and waggles it up and down (as oriented to the photos)
                          In both cases the slide is shown at the top of its travel.
                          This corresponds to a new round having been pushed onto the gun centre line against the two stops which I have already drawn and shown in earlier posts.
                          To pick up a new round the slides would drop down pushed by the end of the feed lever as it rotates to the bottom right position.

                          The good news from these photos is that the feed pawl has no teeth.

                          The crucial bit: changing feed direction from left to right of the gun

                          The pawl slide is ok. Its leg or hook is bolted on and can be on the other side with the slide itself rotated 180 degrees.
                          But what about the feed lever and cam grooves in the top of the breech block!

                          Let's look at the breech block cam grooves and the action on the feed lever with these drawings which come from AP1224 sheets 1 & 2.
                          In the drawings the breech block is bright silver and the feed lever in green.

                          For the breech cover photos above we were looking up.
                          For these two Ap1224 drawings we are looking down.

                          So the top AP1224 drawing is the one that corresponds to the breech cover photos with the breech fully forward and a round on the centre line of the gun. The feed is from the left of the gun.

                          With the bottom AP1224, the breech block has gone to the back of the gun.
                          The knob on the feed lever has followed the groove through the turntable and has pushed the feed slide to its topmost position ready to pick the round waiting and held by the retaining pawl (see earlier posts)
                          There are two grooves with a steam engine turntable in the middle. One of the grooves is for a feed from the left & one from the right.

                          If the feed lever pivot was on the centre line and without the kinks shown on the right hand arm, just changing the turntable and using the second groove could not do the job of changing to a feed from the right. A new feed lever would necessary.

                          I think that's avoided cleverly by offsetting the lever pivot and kinking the arm of the lever. But I need to prove that.

                          Oh wow! my head is spinning. At least there are no teeth to draw.
                          Last edited by MikeHoulder; 19th January 2015, 06:59.


                          • Forestfan
                            Rank 5 Registered User
                            • Dec 2005
                            • 92

                            Dear all,

                            I wonder with your Browning knowledge if I could draw your attention to my thread here?


                            Hoping that if the gun can be identified I may find out where it was issued to, which may help lead to a lost Hampden.

                            Many thanks



                            • MikeHoulder
                              Rank 5 Registered User
                              • Dec 2009
                              • 245

                              Forestfan, I've seen your thread. Unfortunately I don't have any of the knowledge that you want. My interest is purely in the mechanism of the machine.
                              Best wishes & good hunting


                              • roncl
                                Rank 3 Registered User
                                • Oct 2015
                                • 7

                                Great information, guys!

                                I am also very interested in this subject, and have a couple of questions regarding the .303 Brownings that were mounted in the wings.

                                1) When the Mk lll muzzle attachment was used, was the muzzle choke always used?
                                2) How did the cooling fins work?
                                3) Why did the barrel jacked for the .303 have the horizontal slots versus the holes that were used on the US .30 cal guns
                                4) Can someone either repost or send me via PM the photo bucket pictures that were attached in some of the earlier posts? I can't see them. Or if you would rather e-mail them, send me a PM and i will provide you with my e-mail.

                                Thanks guys!
                                Last edited by roncl; 1st May 2018, 20:58.


                                • roncl
                                  Rank 3 Registered User
                                  • Oct 2015
                                  • 7

                                  Referring to Post #11, I believe this picture shows the .303 fitted with the early Mk ll muzzle attachment. Does anyone have an explanation as to why it was replaced with the Mk lll muzzle attachment with the cooling fins? Thanks.

                                  Last edited by roncl; 1st May 2018, 21:05.


                                  • AVI
                                    Rank 5 Registered User
                                    • Oct 2004
                                    • 329

                                    Mike, the Bentley drawings are virtual works of art.
                                    Yes, this is the .50 M2, but it might be of interest to you.



                                    • B25CLIVE
                                      Registered User
                                      • Jan 2019
                                      • 1

                                      Mike, are your Browning drawings available for purchase?


                                      Unconfigured Ad Widget